PHP Result Object

A PHP implementation of Rust's Result type with roughly the same API.

Installation

composer require prewk/result

Overview

use Prewk\Result;
use Prewk\Result\{Ok, Err};

function someApiCall(): Result {
    // ...
    if ($apiCallSuccesful) {
        return new Ok($results);
    } else {
        return new Err($error);
    }
}

function anotherApiCall(): Result {
    // ...
    if ($apiCallSuccesful) {
        return new Ok($results);
    } else {
        return new Err($error);
    }
}

// Fallback to value
$value = someApiCall()->unwrapOr(null);

// Fallback to result and throw an exception if both fail
$value = someApiCall()->orElse(function($err) {
	return anotherApiCall();
})->unwrap();

// Throw custom exception on error
$value = someApiCall()->expect(new Exception("Oh noes!"));

Helpers

Optional global helper functions exist to simplify result object construction:

ok(); // new Prewk\Result\Ok(null);
ok($val); // new Prewk\Result\Ok($val);
err($e); // new Prewk\Result\Err($e);

Add the following to your composer.json:

{
    "autoload": {
        "files": [
            "vendor/prewk/result/helpers.php"
        ]
    }
}

API deviations from Rust

Exceptions

If an Err containing an Exception is unwrapped, that Exception will be thrown. Otherwise a generic ResultException will be thrown.

apply

If all results are Ok, give them to the contained callable value as arguments and put the callable's returned value in a new Ok. If any result is an Err, return the first Err.

$sum = function(int $foo, int $bar): int
{
	return $foo + bar;
}

ok($sum)->apply(ok(100), ok(200), ok(300)); // Ok<600>

ok($sum)->apply(ok(100), ok(200), err(new Exception)); // Err<Exception>

with

The with method will include the variadically added arguments in consecutive closures (map, andThen, etc). This is useful when chaining dependent ops.

ok($foo)->with($bar, $baz)
	->map(function($foo, $bar, $baz) {
		return $foo . $bar . $baz;
	});

Gotchas

Note that or and and will be evaluated immediately:

// This will call all three api calls regardless of successes/errors
$this
	->apiCall()
	->or(anotherApiCall())
	->and(thirdApiCall());

See andThen and orElse for lazy evaluation.

License

MIT & Apache 2.0